pkgs.rustPackages.buildRustPackages.packages

The following is the current implementation of this function.

self:
      let
        # Like `buildRustPackages`, but may also contain prebuilt binaries to
        # break cycle. Just like `bootstrapTools` for nixpkgs as a whole,
        # nothing in the final package set should refer to this.
        bootstrapRustPackages =
          if fastCross then
            pkgsBuildBuild.rustPackages
          else
            self.buildRustPackages.overrideScope (
              _: _:
              lib.optionalAttrs (stdenv.buildPlatform == stdenv.hostPlatform)
                (selectRustPackage pkgsBuildHost).packages.prebuilt
            );
        bootRustPlatform = makeRustPlatform bootstrapRustPackages;
      in
      {
        # Packages suitable for build-time, e.g. `build.rs`-type stuff.
        buildRustPackages = (selectRustPackage pkgsBuildHost).packages.stable;
        # Analogous to stdenv
        rustPlatform = makeRustPlatform self.buildRustPackages;
        rustc-unwrapped = self.callPackage ./rustc.nix {
          version = rustcVersion;
          sha256 = rustcSha256;
          inherit enableRustcDev;
          inherit
            llvmShared
            llvmSharedForBuild
            llvmSharedForHost
            llvmSharedForTarget
            llvmPackages
            fastCross
            ;

          patches = rustcPatches;

          # Use boot package set to break cycle
          inherit (bootstrapRustPackages) cargo rustc rustfmt;
        };
        rustc = wrapRustcWith {
          inherit (self) rustc-unwrapped;
          sysroot = if fastCross then self.rustc-unwrapped else null;
        };
        rustfmt = self.callPackage ./rustfmt.nix {
          inherit (self.buildRustPackages) rustc;
        };
        cargo =
          if (!fastCross) then
            self.callPackage ./cargo.nix {
              # Use boot package set to break cycle
              rustPlatform = bootRustPlatform;
            }
          else
            self.callPackage ./cargo_cross.nix { };
        inherit cargo-auditable;
        cargo-auditable-cargo-wrapper = self.callPackage ./cargo-auditable-cargo-wrapper.nix { };
        clippy-unwrapped = self.callPackage ./clippy.nix { };
        clippy = if !fastCross then self.clippy-unwrapped else self.callPackage ./clippy-wrapper.nix { };
      }